What is the AMPK signaling pathway?

AMPK exists as a heterodimeric complex made up of a catalytic alpha subunit and regulatory beta and gamma subunits. This pathway is a highly conserved sensor of intracellular adenosine nucleotide levels that becomes activated when even small decreases in ATP cause relative increase in ADP or AMP. ATP levels may deplete due to stresses such as low glucose, ischemia, and hypoxia. In response to this, AMPK promotes catabolic pathways to form more ATP and to inhibit anabolic pathways.  The binding of AMP to the gamma subunit activates the complex. AMPK pathway is essentially a central regulator of cellular energy homeostasis. It plays key roles in regulating growth, as well as in cellular processes such as autophagy and cell polarity.